Fecundity calendar



J m- 7, 19 G. H. HEETBRINK ETAL 2,819,021

FECUNDITY CALENDAR Filed Feb. 23, 1954 JNVENTORS GERRIT H. HEETBRINK COENRAAD VAN EMDE BOAS wdzfigwyw United States Patent FEC-UNDITY CALENDAR 'Gerrit Hendrik Heetbrink, Haarlem, and Coenraad Van Ernde Boas, Amsterdam, Netherlands Application February 23, 1 954,'Serial No. 411,974

3 Claims. (Cl. 235-86) The present invention relates to an indicator for determiningthe period during which a woman is capable of conceiving, which indicator is based on the division of .a cycle-into three periods viz. the first infertile period, the fertile period and the second infertile period.

A knownindicatorof this type :is based :on the =O,g ino- .Knaus" method. Thismethod starts from the division of the ripening cycle into three terms viz; the first infertile period, the fertile period and the second infertile period.

In said method use is made, for example, of thefollow- .ingforrnulae:

in whichfL. M. represents the date of the latest menstruation, n represents the number of days of the shorter cycle and m the number of days ofthe longer cycle.

We have now .found that the. above formulae do not .holdggood for all cases. According to the supplementary method discovered 'by Dr. Van 'EmdeBoasafew days .are still added to the last day of .the fertile periodafter .the determination of the fertile and infertile periods according to the Ogino-Knaus method and the number .of said additional days may vary withthevariable duration of the so-called longer cycle.

In the case ofa longer cycle of 2.6 days, for example, 4 days are added; 3 days are added when the longer cycle covers 27 or 28 days; to a cycle of 29 or 30 days 2 days are added; to a cycle .of 31 or.32 days lday is vaddedyetc.

A condition for the application of the supplementary Van Ernde Boas method is that first the duration of .12 successive cycles be determined experimentally to thus -.obtain the values of n and n These are the periods from one menstruation to thev next menstruation. Thefirst day of a subsequent menstruation is reckoned to be'longto the .following cycle.

The object of this invention is to adapt an indicator .of the type described to the improved van Ernde Boas method.

'For this purpose the indicator according to the invention comprises a date scale admitting of being set .for any given date .as the latest menstruation date and covering .atleast another 35 days beyond saiddate, ascale for indicating a shorter cycle, a scale for indicating a longer cycle, said indicator furthermore comprising a window for setting a date, said window and said date scale being relatively movable, adjustable means for indicating the end of the first infertile :period and adjustable means for indicating the beginning of the second infertile period, said two means being adjustable by means of the first and the second scale respectively, the arrangement being such that while the date scale is freely movable relative to the remainder of the indicator the adjusted indicating means admit of being arrested relative to the date setting window.

A practical embodiment of said indicator which meets the above conditions and which so indicates the fertile period that it can be easily read therefrom may be charappropriate legend which has an illuminating effect;

Patented Jan. 7, 1958 acterized according .to the invention by a date band longitudinally movable over a support, a stationary zero index for. said date band, two cursors adjustable over said support andsaid date band and a plurality ofnumbers provided on said support in connection with the variable duration of va menstruation period, by means of which numbers the one cursor is set for the shorter and the other :cursor for the longer menstruation period observed,

the numbers provided on the support being arranged in twoseparate groups of .numhers relating to variable values of .the longer and the :shorter menstruation period respectively, said cursors each being provided with an opaque portion covering said date band.

Of the one group of-numbers relating to the variable valuesof. n each rimin, number may be added to the graduation, .-n -.19 40f .a regular scale having the 'zero index for its zero point.

Of the other group ofrnumbers relating to the variable values of n,,,,,, each 11 number may be added to the graduation n -12+t of the same regular scale having the zero index for its zero'point, 't having an experimentally determined value wlfichis variable in dependence on the value of n If the cursors are nowso adjusted that the opaque portion of the one cursor commences 'at the graduation to which 11 has been added and that theopaque portion of .the :other cursor ends at the graduation to which 11 has been added, which opaque portions overlapmore or less, a portion of the date band will be covered, which portion corresponds with the fertile period.

By arranging the. .two groups of numbers. .in two separate-series i-t is possible -'to provide said'groups with an It .is.also;p.0.ssible.now=to give :each group adistinctive-colour.

The indicator described is very simple and also easily operable.

The drawing illustrates the invention andin the draw- Figure 1 shows a-vertical cross section of an indicator according .to the invention;

Figure 2 shows a vertical section normal "to theuone according to Fig. 1; i

.Fig- 3 shows .aview thereof .as seen looking :to the circumference of the dateband;

Fig- 4 ,in .a side view illustrates the provision of the numbers relating to the menstruation cycles along the edge :of aside face of the indicator.

The indicator according to Figures 1-4 comprisesa cylindrical .flat box divided into symmetrical halves in its circumferential direction. Said two halves are connected each other by a central screw bolt 1 The reference...-numeral' 2 designates a spool whichhas its endsrotatably mounted in holes in the .discs 3 and 4 forming the. bottoms of the box halves. The one end .5 ofthespool projecting beyond the .box constitutes a knob by means ofywhich the spool canbe rotated. A second spool 6 is mounted .for .rotation in the same manner as the. first spool andis located diametrically opposite. the first spoolrelative to the screw bolt 1. .Said spool may .be rotated. by turning the projecting end]. To each spool one end of a date band 8 is secured, which date band iswound a. number of times on each spool and which leaves the, box through an opening 9 in the .cirournference. thereof. and which on either side of said opening surrounds the circumference of the box in a closed loop. On the circumference of the box a window 10 is mounted and two covering cursors 11 and 12 are so mounted on the box as to be slidable in the circumferential direction thereof. The date band passes beneath the window 10 and the covering cursors. Said band rests in a circumferential groove 13.

On the date band the dates of 15 successive months represents the day and the second number the month. The first twelve months are those of a normal year, the last three months, viz. January, February, and March are provided because February 29 has been included for a leap year. In order to avoid mistakes the background on which said three months appear may have a colour other than the colour used for the background of the twelve months of a normal year.

On the, or on each of the, flat bottoms along the circumference thereof numbers relating to the menstruation cycles are arranged (vide Figure 4). In elucidation thereof the following may serve:

If the latest fertile day is calculated by means of the formula L. M.+n 12 this gives for a longer cycle of n =26 days:

L. M.+ (26-12) =L. M.+ 14

For 27 days this is L. M.+15 etc. and for 36 days L. M.+24. To these numbers the safety additions according to Van Emde Boas are still to be added. These safety additions are for a longer cycle of 26 days: 4 days 27 days: 3 days 28 days: 3 days 29 days: 2 days 30 days: 2 days 31 and more days: 1 day If these safety additions are taken into account in making the first-named calculation the latest fertile day in the case of a longer cycle of 26 days will be: L. M.+14+4= L. M.+18 27 days will be: L. M.+l+3=L. M.+18 etc. 36 days will be: L. M.+24+1==L. M.+25 etc.

(28,29); 20 days (30,31); 21 days (32); 22 days (33),

etc.

Thus the settings are obtained for the covering cursor belonging to the longer cycle, so to the value of n These settings are indicated by the notches 14 shown in 'Figure 4 at the right hand bottom side, which notches are provided with indications of the values belonging to n It should be noted that not all of the notches actually used in practice have been shown, but only enough to illustrate their position on the device.

For the cursor belonging to the shorter cycle, so to the value of n one may proceed in a similar manner.

These settings for said last-named cursor are indicated at the top of Figure 4 as notches 15 provided with in- 'dications of the values belonging to n Likewise, not all of these notches are shown. Also, in practice, these notches are placed on the other side of the device. When using the indicator the date band is moved so far by means of the knobs 5 and 7 that the date of the latest menstruation L. M. appears in the window (zero index).

The covering cursors 12 and 11 set respectively for the values of a and n holding good for the case under consideration will then cover the days of the fertile 4 period on the date band. In doing so the covering cursors are placed with the leading edges of their opaque portions at the notches against which the relative value of n is marked.

The operation of the fecundity calendar according to Figs. 1-4 is as follows:

The annular slide bearing the indication shortest cycle is displaced so that it is adjusted in accordance with the numeral (e. g. 28) of the shortest cycle. The annular slide bearing the indication longest cycle is then adjusted in accordance with the numeral (c. g. 32) of the longest cycle. By means of the knobs 5, 7 the date band is adjusted so that the indication 11 can be read through the window 10. Arrows (not shown) on the side wall 3 indicate the direction of rotation.

If the adjustment has been effected correctly (cycle 28-32) the following dates can be read successively: 1-1 (Jan. 1); 2-1; 3-1; 4-1; 5-1; 6-1; 7-1; 8-1; 9-1. Then follows an opaque portion whereupon the date scale becomes visible again at 22:1; 23-1, etc. The correct ending of this scale cannot be indicated exactly since it depends on the date at which the following menstruation begins.

In the window 10 the date of the first day of the last menstruation of the woman is adjusted. All of the dates visible are'the dates on which said woman is infertile. All of the not visible dates are fertile days.

We claim:

l. A fecundity calendar for determining the power of conception of women and being based on the division of a cycle into the first infertile period, the fertile period and the second infertile period, and comprising a cylin- 'drical box-shaped casing, a date band mounted within said casing and adapted to be passed over the circumferential wall of said casing, a stationary zero-index on the periphery of said casing over said band, two cursors adjustable over the circumferential wall of the casing and said band and a plurality of numbers provided on said casing corresponding to the variable duration of a menstruation period, by means of which numbers the one cursor is set for the shorter and the other cursor for the longer menstruation period observed, the numbers pro vided on the casing being arranged in two separate groups ,of numbers corresponding to variable values of the longer and the shorter menstruation period respectively, said cursors each having an opaque portion covering said date band.

2. A fecundity calendar as claimed in claim 1, comprising a first shaft mounted for rotation in an upper part of the casing, a second shaft mounted for rotation in a lower part of the casing, one end of the date band being attached to said first shaft, said band being wound a number of times on said shaft, the casing having an opening in its circumferential wall through which the band is lead around the outside of said wall and back into the casing and is wound a number of times on said second shaft to which its other end is attached, the band thus forming a closed loop surrounding the casing, and means for rotating said shafts.

3. A fecundity calandar as claimed in claim 1, in which the two separate groups of numbers are placed along the circumferential edge of a side wall of the casing and the cursors or slides are mounted so as to be slidable or adjustable over one another.

References Cited in the file of this patent UNITED STATES PATENTS 2,577,544 Schenk et al. Dec. 4, 1951 

